Washington (CNN)A top White House aide called Steve Bannon's comments in a new book on President Donald Trump "grotesque" Sunday on CNN's "State of the Union" before anchor Jake Tapper cut him off for not answering questions.

"It's tragic and unfortunate that Steve would make these grotesque comments so out of touch with reality and obviously so vindictive," White House senior policy adviser Stephen Miller said, referring to Trump's former chief strategist.

During the contentious interview, Miller offered largely combative responses and focused on presenting Trump as a "political genius," repeatedly refusing to answer questions until Tapper decided to cut him off and move to the next segment.

CNN has not independently confirmed all the assertions in "Fire and Fury" by author Michael Wolff, which portrays Trump allies questioning the President's mental fitness for office.

Trump on Saturday took to Twitter to defend his mental abilities, saying he is "like, really smart" and a "very stable genius."

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The White House issued a statement Wednesday attacking Bannon as excerpts of the book emerged with quotes attributed to him that denigrated the President and Donald Trump Jr. The book quotes Bannon as saying a 2016 Trump Tower meeting between Trump campaign officials and a Russian lawyer purportedly offering damaging information about Hillary Clinton was "treasonous."

Miller on Sunday echoed the language of the White House's statement to attack Bannon as well as CNN.

"(Bannon's) role has been greatly exaggerated, whereas the President hasn't gotten the due that he deserves for the movement that he put together to tap into the kinds of people whose life concerns don't get a lot of attention on CNN," Miller said.

Miller praised Trump extensively, saying the "reality" is that the President is a political genius and that Trump's Twitter missive declaring himself a "very stable genius" did not undermine the claim.

"The President's tweets absolutely reaffirm the plainspoken truth: A self-made billionaire revolutionized reality TV and tapped into something magical that's happening in the hearts of this country," Miller said.

Trump again slammed the book on Twitter Sunday morning and appeared to reference questions raised about the mental fitness of former President Ronald Reagan, who disclosed in 1994 that he had Alzheimer's disease.

"I've had to put up with the Fake News from the first day I announced that I would be running for President. Now I have to put up with a Fake Book, written by a totally discredited author. Ronald Reagan had the same problem and handled it well. So will I!" Trump wrote.

I've had to put up with the Fake News from the first day I announced that I would be running for President. Now I have to put up with a Fake Book, written by a totally discredited author. Ronald Reagan had the same problem and handled it well. So will I!